RESEARCH QUESTIONS: In longitudinal research, will participant-initiated internet data entry improve 1) participant retention and 2) data quality? RESEARCH CONTEXT: While longitudinal research may be the best tool for examining the course of human health and illness over the lifespan, the burden of participation over many years often results in loss of participants to follow-up. Such attrition reduces statistical power and threatens the internal validity and generalizability of inferences drawn from longitudinal data (Shadish et al., 2002). Because internet data collection is convenient and simplifies complex questionnaires, this method may reduce participant burden and reduce attrition. While internet data collection is already regarded as a viable tool for participant recruitment (Smith et al., 2007) and usually results in data of equivalent or better quality (e.g., factor loadings, reliabilities) than traditional paper-and-pencil methods (Vergnaud et al., 2011), internet data collection as a tool to increase participant retention within an existing longitudinal cohort has not been evaluated previously. The goal of the current project is to determine whether internet data collection increases participant retention and data quality within the APrON (Alberta Pregnancy Outcomes and Nutrition) study.